BB spindle thread (I'm making a DIY tool)
 

What is the threading or pitch for a BB spindle? Looking to build a little DIY splined tool holder with a bolt and some washers.

8MMx1.
8MMx1.25 is more common, but not what you want.

Get a couple different lengths.

I picked mine up at Car Quest, since they were close. The clerk was rather befuddled until he tried bolts out of the "other" 8mm drawer.
IF you have a spare spindle or nut, take it with you.

I've made a similar "tool", using a splined BB remover to also hold a PARK HCW 4 in place.

Bill is correct. The lengths that work are usually 40 mm to 50 mm. If you get a 50 mm long bolt you can use a stack of washers to fill in any gap.

sweeeet! Thanks guys! Home Despot/Lowes weekend for me.

You might have better luck at a "good" auto parts store?

Neither are likely to have M8x1.0 mm bolts as M8x1.25 is far more common. I got mine at a very well equipped local hardware store and, as Bill noted, an auto parts store may be a better bet. If not, you will have to go to an industrial supply house like Grainger or McMaster-Carr or online from Bolt Depot or similar.

Ahhh, okay thanks! I have a few auto stores nearby and also a Harbor Freight. Harbor Freight is where I got my giant Campy crank allen wrench. It was like 3 bucks compared to "bike shop" giant allen wrench . I think its like a 12mm or something (power torque Campy).

Bene Sugg .. might get a better than soft mild steel .. a heat treated bolt @ auto/industrial hardware shop..

The bolt needed to clamp a bottom bracket tool to the bb spindle is not under a lot of stress as all it does is keep the tool from slipping off the splines. Nothing exotic is needed and any 8 mm bolt is pretty strong anyway.